You've gone too far.

Correct!

Here, the perfect is used instead of the simple past when you refer to an action that “crosses the line,” something that changes things forever, something that there’s no coming back from. For instance, say the police was down the street last night and you saw the lights but didn’t know what happened. The next morning, your wife finds out one of your neighbors murdered his wife. When you come downstairs, she can say “Ned killed his wife,” which is just a fact with no emotion. But if she wants to bring out the gravity of what he did, she would say “Ned has killed his wife.” Here again, the perfect is just more emotive - it makes Ned’s act sound more unbelievable, unfathomable and irreparable in her eyes. At the same time, the perfect turns a simple statement into an announcement, something notable, a piece of news, not just a casual fact.

Thank you, got it.
I assume she will choose Present Perfect)
Because the action she is talking about is really irreversible.
Unfortunately...

Exactly

AND it’s an announcement. She knows her husband was curious about why the police were down the street last night and she gives him a “newsflash.”

Ok, thank you very much, clear!